A controller unit of this general type is described in U.S. Pat. No. 5,386,337. The lead wires extend in a potting composition by which the coils are also retained in the housing of the controller units. Only the ends of the lead wires project from the partition wall in the controller unit and are soldered to the printed circuit board. This necessitates a separate production step which involves intricate handling because the components which have already been fitted and soldered to the printed circuit board must not be damaged in this soldering operation. This makes a complicated soldering process necessary or requires the components to be spaced from the location where the ends of the lead wires are being soldered to the printed circuit board. Therefore, the printed circuit board has correspondingly large square dimensions.
The lead wires of two coils, arranged in pairs relative to each other, are deflected so that the ends of the wires are arranged in a row. The current-conveying elements in the printed circuit board and the positioning of the components must be adapted to this arrangement.
European patent application No. 37355 discloses a controller unit wherein the lead wires of the coil extend to a multipoint connector, and the mating connections of the printed circuit board are arranged in a counter plug. The printed circuit board is arranged in a lid, and the plug connection is established when the lid is mounted. This arrangement is relatively complicated because the connections of the printed circuit board and the lead wires of the coils must be led to a multipoint connector.
The above-mentioned European patent application also discloses an arrangement wherein an intermediate ceiling which includes conductor paths is provided in the controller unit. Plugs are arranged on the bottom side of the partition wall and cooperate with guide pins which project from the coil casings. The conductor paths in the partition wall are uncovered at a point so that a connection can be made to the printed circuit board which is attached in the lid of the housing.
A valve control device is disclosed in European patent application No. 658 463 wherein the magnetic coils are inserted into an aperture of the controller unit and retained therein by way of a snap-type locking engagement achieved in the following fashion:
Several arms are attached to each magnetic coil and embrace the coil like a spider. Detents are provided at their ends. Mating indentations are recessed in the apertures permitting snap-type engagement by the detents. This arrangement achieves a slightly swinging accommodation of the magnetic coils so that they may become aligned when mounted onto a valve dome in which the magnetic armature is guided.
The press-in technique for press-in pins in printed circuit boards is described in the leaflet of ept-Gugelhoer Peiting GmbH & Co. Elektronische Praezisions-Technik titled, `ept Einpresstechnik, Tcom Press`, August 1990. This concerns especially solid or formed press-in pins which, in terms of their strength, are adapted to the requirements of relatively great press-in and press-out forces.
An object of the present invention is to design the controller unit of the generic type so that the connection between the coils and the printed circuit board can be carried out quickly, devoid of mechanical and thermal stress, and under the condition of a simple tolerance compensation. The previous coil lead wires are maintained. Another objective is to provide the printed circuit board with the smallest possible square dimensions.
When, in addition, not only the ends of the lead wires of the coils are designed as press-in pins but also the connection to a plug or an electric motor, the printed circuit board is only required to be pressed onto the press-in pins arranged in one plane in order to produce a reliable electrical contact between the lead wires and the printed circuit board.
Further embodiments of the idea of the present invention are described in the subclaims. It is especially important that the forces which are caused in the press-in operation will not be introduced into the coils and that mechanical stress which occurs, for example, in thermal expansions of the materials, will not take effect on the press-in contacts, or only to a certain extent. It is suggested to this end that the lead wires be bent off above the partition wall in the controller unit housing so that the ends of the lead wires are offset with respect to the associated coil. It is preferred that the ends of the lead wires are held in a plastic holder which bears against a base on the partition wall. This base takes up all forces occurring in the press-in operation. In addition, the base causes the ends of the lead wires to exactly adopt a position where they are in alignment with the corresponding insertion holes in the printed circuit board.
As an alternative of the plastic holder, the ends of the lead wires may include locking or fixing elements which, preferably, are designed integrally with the wires and are snap fitted to matingly shaped accommodations on the partition wall.
The lead wires extend uncovered or, possibly, in guides above the partition wall. The advantage is that tolerances can be compensated. The position of the ends of the lead wires is determined by the position of the base so that tolerances in the lengths of the lead wires can be compensated for by slightly bending the wires.
Further, the lead wires or their length and orientation with respect to the coil are aligned to be identical for all coils. This must, of course, be taken into consideration in the positioning of the plugs on the printed circuit board.